Pneumatic compressor bleed valve

A gas turbine engine having a longitudinal engine axis, a compressor housing with a radial surface of revolution about the axis and a bypass duct, the engine comprising:

• a pneumatically operated compressor bleed valve communicating between of the compressor housing and the bypass duct, comprising:
• an annular piston slidably mounted within an annular chamber concentric the longitudinal axis;
• an annular valve plug on the piston and an annular valve seat on the compressor housing defining a valve seal interface;
• and
• a control air pressure conduit communicating between a portion of the annular chamber bounded by the piston and a source of control air pressure.

A fluid pressure operated valve communicating between an interior and an exterior of a containment housing, the housing having a longitudinal axis and a radial surface of revolution about the axis, the valve comprising:

• an annular piston slidably mounted within an annular chamber concentric the longitudinal axis;
• an annular valve plug on the piston and an annular valve seat on the housing defining a valve seal interface;
• a fluid pressure conduit communicating between a portion of the annular chamber bounded by the piston and a source of pressurized fluid;
• and
• a plurality of guide bearings mounted to a periphery of the piston and the housing, the bearings having a helical guide surface concentric the axis.